Hydraulic variable pressure relief valves



Jane 24, 195s F. HLTowLER l-:TAL

HYDRAULIC VARIABLE PRESSURE lRELIEF VALVES Filed Aug. 13. 1953 2 Sheets-Sheet l /f26l v John Mahr-ice. Tauler l 87' ww w# Arme/w75 June 24, 1958 F. H. TOWLER 4ET Ax. 2,840,106

HYDRAULIC VARIABLE PRESSURE RELIEF VALVES Filed Aug. 13, 1953 2 Sheets-Sheet 2 United States Parent' e jz;ws4o,1osjjl j HYDRAULIC VARIABLE YPRESSURE RELIEF? VALVES ,p Franlr Hathrn Towler, Rodley, jandfJohn" Maurice Towler," Doh Park,near Otley, England, assignors to Electraulic Presses Limited, Rodley, England, a limitedliability company A t' y a z' Application August 13, 1953, SerialNo. 373,972 Claims priority, application Great Britain August 22, 1952 4 Claims. (Cl. 1375-538) This invention Irelatesgto hydraulic relief vvalvesof the l. b b1,el' type comprising a va ve mem er Whlch 1S mova e 'r a 11 into whlch projects thev inner end of the lever 5 for tively to inlet 'and outlet ports and is acted upon at one. end by the pressure liquid'to movethe same against a spring load to `connect said ports Vand provide a passage to exhaust for the pressure liquid when it reaches a pre-vv determined pressure.A- ySuch pressure is :usually termed the blow off pressure ofthevalve. l Y

In relief valves of the above'type as now commonly constructed the blow oi pressure. is, carriedl by adjustingpthe compressionuofv theu'spring by meansrof a hand wheel acting through a screw andan engaging nut.

The objectlof the presentginvention, is;to provide` az, relief valve having improved meansfor adjusting theA blow loll pressure which will permit the adjustment to bev 4ishunder load, by

eected at will, even when lthe Vvalve a simple hand or foot operated lever.

outlet ports that are: opened,V and closed vby the, valve member are` formedlina member which, is movable relaf tively to and'independently of the spring loaded valve at which the valve will .blow ott.

A hydraulicrelief valveaccording to-'apreferred emr-- bodiment of the invention comprises, in combination, a valve casing vhavinga boreand laninlet;'andioiitlet for pressure liquid, said inlet andjoutlet ,beingiseparated from each other an'd communicating with'said hofmanI annular sleeve fitting slidably vin said 'bore and E arranged to be in hydraulic ybalance so as to bemovable 4longitudinally therein, preferably by- -aV direct" acting hand or foot operated lever on the outside ofthe valve' casing, ports in the wallrof saidgsleevewhich provide further inlet `and outlet passages "for thepres'sre liquid and a valve spindle -which -is a close-Slidingiit in the central bore of the annular sleeve said valve spindle being movable against a spring load relative tothe sleeve by pres?y sure of the pressure liquid acting on an area at one end of the spindle, said movement producing a gradual increase in the spring load and being from a position where the valve spindle isolates the ports in the sleeve from each other to another position where a connectionY between said ports is established yand the pressure liquid is free to exhaust, the arrangement being such that by relative movement of the sleeve the extent to which the spring is compressed when the valve spindle has moved to the exhaust position is varied at will and therefore the pressure which the pressure liquid has to reach'before its release to exhaust by the valve can take place.

In order that the invention may be clearly understood` and carried into effect an example according to the above embodiment will now be described by aid ofthe accompanying Vdrawings in which:

Fig. 1 is a vertical section through the improved relief valve.

VJPatented.` JuneY` 32,4, 197.5@

Fig. 2 lis a transverse section on the Aline'L B 'B of Pig. 1 and,

. Y2, valve spindles 3 and 4 and a lever 5 which may be operated either vby hand or by foot.

l .The valve body 1 has a through bore 6 which is closed at its upper e'nd by a spring casing 7 and at its lower end by av base plates; the ported sleeve 2 is a sliding lap-lit in the through bore 6.

The through'borev is enlarged toprovideran annular` chamber 9 which `is connected to exhaust anda further annular'chambe'r 1 0 which is connected byaninlet to the pressure liquid.v At the lower` end of the through bore 6 there is provided a `s till f urther annular chambert the, purpose ofVV engaging thellower end yoflthe ported sleeve 2. The' chamber `11 communicatesmby means of passages12 with the interior of the jspringficasing 7,

. 4 which spring casing inV turn is connected Vto, exhaust by aA drain connection13. As the upper end ofthe through4 bore is permanently open to the interior offth'elspring casing 7 by ports 14 in aY springpad '23; bothfends of theA portedsleeve'will thus be'connected to exhaust, and,

. in consequence, will lalways' by in hydraulic balance`-k i fThe' y'sleeve isr'thus' always'rnovable with a minimumv ot`- 1,5, 16 and' 1,7fres`pe'ctively, each set being ata diiferentf Aposition, and the radial ports 17 alsoico'mmunicate withl` Broadly the present invention .consistsmofv4 a hydraulic;- Y helght mathe length of the Sleeve 'Whreby the radial-'portsrelief valve Vofthe above ,type in which the inlet' and 15l communicate fat all positions vof thefsleeve with the annular exhaust chamber 9, Vthe'radial ports 16 with the pressurey chamber 10 ,when the sleeve is in the lower thepressure chamber. 10 when the sleeve is invits uppergY position; 4The sleeve 2 has'a'through bore 18in which the valve spindles 'v3 and 4 are va lap-fit and such bore has 'a portionl ofi'ncreasefd;diameterfto :provide an annular spaceLkr 19 surrounding1 the opposingjand meetingends ofhthevalve spindles and adapted r-to ybe supplied with'pres's'ure liquid"V by the radialports 16 and' 17in turn. To provide the, necessary areas on the valve spindles' against which theY 4 pressure 'space- 19 can act, said valve'spindles, aty their Aopposingendsare'lformed with reduced portionsy 20.A The` aforesaid areas are indicated at 21., `The, ac tion fof?, th'pressurewithin the space 21 '.whenfacting aygain'st'theare'asfZlo n the `valve 'spindles' is to holdrthef lower -v alve s'pindlef onits seating 22 and to press the` upper valvespihdl lv4 againstthe spring'pad'23 as showin in Fig. l, the spring pad 23 comprises a disc-shaped body i ypierced by a series of ports 14 and slidably received in sok the spring casing 7. The underside of the pad is formed centrally with a conical socket 14a for reception'of the upper end of the spindle 4. A spring cup 23a is formed with a' ange adapted to rest on the pad and provide a seat for a spring 24 interposed between the ilange andl the end of the casing 7. The spring 24 yieldably urges the pad 23 into engagement With the end of the'housing 1 which thus serves Vto define one limit position of the pad. A stop sleeve 23h carried on the t-opof the spring cup coacts with the upper end of the casing 7 to defineV the other limit position of the pad. VWhen the pressure within the space 19 reaches a predetermined valueV this a spring 24 within the spring casing 7 until itreaches a position where theupper set of radial ports 15 have their inner ends opened to the space 19 by way of the reduced inner end of the valve spindle 4, see Fig. 3, and thus 1 `will be correspondingly increased and also thepressure which the liquid within the chamber 'w`illllhave toat'tlain before such release `can take place.

2 to be moved by thelever'into and out'oftfwofek! treme positions andth'ese are determined by limiting st ops 25 and 26;' the stopZS beingcontacted uhy the inner end Y of th'eilever 5 to limit the downward movemeiitiofi'the to beginphyidraulic balance sofs tofbe `movable longif" tudiiially thereimpreferablyhy a direct por, foot :operated lever Yon the outside lofthe valve casing,`

portsfin Y the wall ofsaid Sleeve which', provide AVfurtherA niet, jan-d1 ,onder :passages for P ssurg liquid,i aan: ,sf valve .spindle which is close 'sliding lfit inthecentral bore of the annular sleevesaid valve jspindlezbeing mov'- abxle `fagainstaspring',loadrelatiiveto the sleeYqbYpres-- surefef the pressure liquid actingV'nfanarea at one 4endV of the Ispindle, said movement ,producing Y a gradual- -in.

creaseiin the spring load and being frornapositiomwhere the" valve spindle isolatesl thek ports in the sleeve from each other to another po's'itinwhere a connection-hb` i tween Vsaid` ports` is ,establ,ishedsand they pressui'e'rlifllliildk i,S free to exhaust, the arrangement being such that by relative movement of the sleeve the extent to which the spring is compressed when the f valve spindle has movedtojthe exhaust position is .variedeat will and therefore-the presl-` ee lh the pressureliquid to reach,before its E release toexhaust by the uvalve can take place. l

sure fwhf `2'." A ,hydraulic reliefvalve according to claim, 1, having two stops which limit thermovement 7of, 'the sleeve to two extremeV positions corresponding.;respectivelyto @minimum blow olf pressure` arida maximumblowolf pressure,

said sleeve being provided'with'threeisetsJof radial :ports in itslengthdand saidv bore being formed interiorlymwith Y two annular recesses, one Vrecess being permanently open to the pressure liquid `inletin i the jcasingand one set, of-` radial ports in the sleeve withan `adjacent set of radial ports closed by the wall of 'the bore in the casing and the other annular recess being permanently open to the exhaust outlet in thecasin and the third set of radial ports in the sleeve, the arrangement being such that with the sleeve in the position` of minimum pressure exhausting takcsplace through thep'orts which are normally open to b'othlan'nul'ar. recesses `"and in' theposition ,of maximum pressure exhausting takes'plaoethrough the set of radial ports normallyA closed to the inlet by the wall of the bore inthe casingi'and the radial portswhch are 'permanently open to the exhaust'outlet.

3. A hydraulic relief valve comprisil1g,in` combination, ra'valve bodyhaving a bore with inlet and outlet The `valve'illustrated is designed to enable the` sleeve passages openin'gthereto,lr a` sleeve memberslidably fitted in said bore having Aradially disposerdports-open to the respective passages,` a valve-spindle reciprocable in said sleeve member between `openfand closed'positions to es- L tablish or interrupt communication between said passages posed tothe pressure at -the inlet passage and tending to shift it toward 4ope'n position,gspring means interposed between the valve body and" thiefother e'nd ofsaid spindle to resis'trmoverrientrto openpostion, and rneansfor Ashifting said sleeve member `valorigsaid bore` and relative to saidfspindleto determine the pressure at theV inlet passage required to overcome theifo'rc'eof said spring means and effect movementof the valvespindle to open position.

A 4. Ahydraulie reliefivalvecomprising; in combination,-a -v-alve-bdy having a -borefwith inlet and outlet passages opening thereto, a sleeve Vmember Vfitted in said bore and-slidable therein`- between twolirnit positions,

said sleeve l member havingl ports open to `the respective passagesirithe valvebody, afvalve lspindle reciprocable in said sleeve memberibet'weenopen and closed positions to establish or interrupt communication between said-passagesfby way Aof saidports, Aa spring biased pad positioned for engagement; by 'e one l'end' ofl said spindle n upon' movement towardl open position, said pady Abeing spacedjfrorn said spindleso as to permit'unopposed` movementof-the Ispindle togopen-positon when said sleevc member is in one limitfposition;"andjsaid spring biased pad applying progressively fincreasng resistance to the' movement of the spindle to'open position'as said sleeve memberfis shiftedtoward itspther limit position r Reference'svCitedimthe-le of this patent y i UNirED STATES TATENTS 

